Even more Team Fortress 2!

TF2: RED IRL. Photo courtesy of Google Image Search.

I'll admit that after Portal 2 came out, I had already been playing less and less TF2- I'm back to multiclass play- I've lost grip on whatever magic I had with demo/pyro strategies, so I'm learning to use the other classes- I'm pretty good with everyone but the spy (which is, from what I understand, the most difficult class to play well).

If anyone has links to some good playthrough or strategy for any class, I'd totally appreciate a link in the comments.